1. Field of the Invention
The subject invention generally relates to an acrylic resin and method of forming the acrylic resin. More specifically, the acrylic resin of the subject invention is useful in fluorocarbon coating compositions.
2. Description of the Related Art
Fluorocarbon resins, such as polyvinylidene fluoride (PVDF), are useful in formulating coatings with excellent weathering resistance. It is common to add binder resins to fluorocarbon coating compositions because fluorocarbon resins have poor rheology and pigment wetting characteristics. Typical binder resins that have been previously utilized with fluorocarbon coating compositions include acrylic resins Such acrylic resins are preferred for many applications because of the improved mechanical and chemical resistance that are provided as a result of incorporating the acrylic resin therein.
To achieve optimal weathering and chemical resistance, high fluorocarbon resin content is desired in the coating compositions. Many coating applications call for coating compositions having 70 weight percent or more fluorocarbon resins and the remainder is the binder resin. Coating compositions containing fluorocarbon resins, particularly PVDF, and acrylic resins as the binder resins tend to have relatively high viscosities. For some coating applications, particularly coil coating applications, it would be desirable to have high fluorocarbon resin content in conjunction with the acrylic resin, but with lower viscosity than is currently possible with the related art compositions.
In order to provide desired pigment wetting characteristics, some related art methods have manipulated the acrylic resin during formation. For example, the acrylic resins have been polymerized from acrylic acids and acrylic esters having no additional functionality, acrylic acids, and acrylic esters having additional functionality, and an acryloxyalkyl oxazolidine. The functional acrylic acid/esters provide sites for cross-linking with cross-linking agents. The acryloxyalkyl oxazolidine reduces the viscosity of the fluorocarbon resin and acrylic resin. One specific acryloxyalkyl oxazolidine that has been previously utilized is 3-(2-methacryloxyethyl)-2,2-spirocyclohexyl oxazolidine (MESO). The MESO monomers are becoming increasingly difficult and/or more expensive to obtain due to the high cost of manufacturing Other attempts to lower viscosity of the acrylic resin have included polymerizing and/or reacting the acrylic resin with polyimides, amino groups, epoxy groups, and the like. However, these modified acrylic resins do not perform as well as acrylic resins modified with MESO.
Accordingly, it would advantageous to provide an acrylic resin that adequately lowers viscosity and that provides desired pigment wetting characteristics when incorporated into a coating composition. Further, it would be advantageous to provide a method of forming the acrylic resin from monomers and starting components that are commercially available and that are relatively inexpensive such that manufacturing coating compositions that include the acrylic resin is not cost prohibitive.